407117: GYM102697 088 Radioactivity

Memory Limit：256 MB Time Limit：1 S
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Description

088. Radioactivitytime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard output

Radioactivity

You're trying to determine how many neutrons are in a certain radioactive isotope. You know how many protons are in the isotope, and you know the isotope's mass number. The mass number of an isotope is defined as the number of protons plus the number of neutrons. Given the number of protons and the mass number, figure out how many neutrons are in the radioactive isotope.

Input

The only line of input contains two space-separated integers $$$p$$$ and $$$m$$$ ($$$p$$$ <= $$$m$$$), representing the number of protons in the isotope, and the mass number of the isotope, respectively.

Output

Output a single positive integer $$$n$$$: the number of neutrons in the radioactive isotope.

ExamplesInput
92 238
Output
146
Input
36 85
Output
49

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